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Please consider me as a naive self-learner in this field.

The Standard Model (SM) Higgs boson is electrically neutral and has a mass of around $125$ GeV (which lies in the WIMP window i.e., between 10 GeV to 1TeV). Why is then it is not a candidate of dark matter?

  1. Surely it can decay into SM fermions and gauge bosons. But are we sure that the decay modes are not kinematically forbidden or insignificant so as to explain the present relic abundance?

  2. As I said that the Higgs boson mass lies in the WIMP mass window. How is it then different from a WIMP?

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  • $\begingroup$ It may however decay into a dark matter particle that is stable. I believe this is a valid hypothesis. Atlas is actually experimenting on this hypothesis. But there was no update on the project since 2020. If you want to keep track of this project follow this link: atlas.cern/updates/briefing/probing-dark-matter-higgs-boson $\endgroup$
    – Markoul11
    May 11 at 19:10

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Higgs would quickly decay to a mix of products, many of them electrically charged. Thus dark matter is neither Higgs nor former Higgs.

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  • $\begingroup$ I apologize for my ignorance. Higgs boson is not present in the present Universe, only the Higgs field is. And it requires a particle collider to produce them. However, as I understand, dark matter particles are present in the halos of the galaxy. Is that correct? @J.G. $\endgroup$
    – SRS
    Dec 16, 2017 at 13:23
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    $\begingroup$ SRS, dark matter should be composed of particles with a long lifetime, or if it is short the only decays should be in other weakly interacting particles. The Higgs is not a candidate because it decays fast to hadronic channels and also to gamma gamma. It will not have survived from the symmetry breaking time in the cosmological history. $\endgroup$
    – anna v
    Dec 16, 2017 at 15:44
  • $\begingroup$ @annav Can you give the theoretical expression for the decay width of Higgs to $\gamma\gamma$ and from that an order-of-magnitude estimate of its lifetime? $\endgroup$
    – SRS
    Dec 17, 2017 at 5:21
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    $\begingroup$ @SRS it is not that simple. You can find how they give a limit in CMS data from the decay to four leptons in cds.cern.ch/record/2037207/files/arXiv:1507.06656.pdf . the method is explained. The expected from theory lifetime is in femptoseconds. $\endgroup$
    – anna v
    Dec 17, 2017 at 5:40
  • $\begingroup$ @annav So if the Higgs Boson is so unstable how it can sustain an omnipresent Higgs field? $\endgroup$
    – Markoul11
    May 11 at 18:45

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